l90 EFFECTS OF PORBaTS ON SPBINQS AND RIVERS. 



ever increased in that those high floods now occasion more frequent 

 and more disastrous inundations." 



Herr Wex goes on to say: — "Having in foregoing statements given 

 indisputable evidence that in the five principal rivers of Central 

 Europe, — the Danube, the Rhine, the Elbe, the Vistula, and the 

 Oder, the basins of which embrace an area of 26,860 [German 1] 

 square miles,* — the lowest and the mean annual water levels, and 

 consequently also the quantities of water delivered by these rivers, 

 during a lengthened period of many years, has been continually 

 decreasing, we may^from this draw the following conclusions : — 



"1. As the aforesaid rivers are fed mainly by the brooks and 

 streams which flow into them, there must have been also in these a 

 continued decrease in the quantity of water delivered by them for a 

 great many years, from which we may further conclude that if observa- 

 tions had been made on the levels of the difierent feeders, 

 similar to those which have been made on the five large rivers named, 

 and these had been compared, they would have supplied results 

 similar to those at which we have arrived concerning these. 



" The correctness of this allegation receives confirmation from the 

 fact that many manufactories, &c., which have been built during the 

 last fifty years, on rivulets and streams, have experienced a marked 

 diminution in the quantity of water coming through their water- 

 leadings, and it has been found necessary to employ steam-engines to 

 meet the deficiency of their water power, which was originally 

 -sufficient for the work they had to do. 



" 2. As it is possible that the causes which have produced the 

 effect of the lowering of the water level, and diminution of the 

 quantity of water delivered in these five river basins, operate 

 equally in the basins of the other rivers and streams in Europe, and 

 not only so but in the most populous and cultivated districts of the 

 other three quarters of the globe — it may be assumed that in most of 

 the streams and rivers on the surface of the earth a similar lowering 

 in the lowest and mean levels of the body of water delivered by them 

 has taken place ; while the high floods in the same, reaching a higher 

 point, and becoming of more frequency, discharge a greater quantity 

 of water, and produce more extensive devastating inundations than 

 previously was the case. 



" 3. If the causes which have operated in producing the decrease of 

 the usual water flow of the streams and rivers, with the rapid over- 



* A German mile is equal to i^ English miles. 



